In 1980, The Planetary Society was born out of the minds of Carl Sagan, Bruce Murray, and Louis Friedman, as a non-profit organization with a focus on public outreach and a dedication to sponsor innovative projects to further the exploration of space. Currently, The Planetary Society is directed by none other than Bill Nye of Science Guy fame. He has helped guide research projects that are now realizing Sagan’s dream of solar sailing in space.
In 2005, Cosmos 1 was The Planetary Society’s first attempt at launching a solar sail. In 2009, they launched another sail under the NanoSail-D project. Both attempted launch vehicles failed to reach orbit.
Six years later, now under the project name, LightSail, the first successful test flight launched on May 20th aboard the Atlas V rocket from Cape Canaveral Air Force Station in Florida. While the satellite will not be high enough to fully test solar sailing capabilities, the current plan is to test deployment procedures and communication systems. LightSail is planned to officially launch in 2016 with the Falcon Heavy rocket built by SpaceX.
While rocket propulsion is required to launch spacecraft into orbit, most spacecraft then still rely on engines to thrust toward its trajectory course, as well as maintain proper attitude control—minor adjustments so that the satellite is facing proper direction toward Earth or whatever object in space. Yet, maintenance of engines and exhaustion of fuel is costly and slow, and other methods of propulsion are being explored. LightSail was developed as a proof of concept for solar propulsion in space.
The mission is to launch a CubeSat—a small, cost-efficient satellite the size of a loaf of bread—with a 32m2 kite-shaped solar sail that could fill the floor plan of a small apartment. Once in space, the four panels of the solar sail will be deployed. The sail is made out of a reflective Mylar material which captures light momentum from the sun.
Light is made up from elementary particles called photons. Photon particles do not have mass, yet they have energy and momentum. Momentum is classically defined as mass times velocity (p=m*v), which presents a paradox in this context—light travels in a stream of photon particles, suggesting they have momentum, yet photons have no mass. However, velocity has a limiting factor: the speed of light. Albert Einstein theorized that since photons travel at the speed of light, that the rules of special relativity must apply (it was actually this work, not the more famous theory of relativity, that earned him the Nobel Prize in Physics in 1921) and photon momentum is actually defined by Planck’s constant divided by wavelength (p=h/λ). Since light is a continuous source of energy, the transferred momentum on the sail provides continuous thrust, allowing for greater speeds over time when compared to short bursts of rocket-fuel.
As of May 26th, the LightSail test mission is on hold due to a communication glitch with the spacecraft’s software. Until a reboot is possible, testing of the sail deployment procedures is on hold. However, the spacecraft is still happily in orbit, and can be monitored via radio tracking. As a non-government organization, The Planetary Society welcomes any amateur citizen scientists to participate in observing and collecting data via radio tracking.
Additionally, LightSail is a citizen funded project, using the crowdsourcing website Kickstarter to collect funds. This emphasizes the importance of public support and collaboration from ALL people—not just the old men in lab coats. The campaign has already met it’s goal, but stretch goals are still on the horizon as we close in on their June 26th deadline.
If you don’t have the skills to track radio frequency data, or don’t have the funds to contribute to the LightSail campaign, there is still opportunity to get involved. Voyager’s Golden Records were launched into space in 1977, providing a snapshot of Earth and human culture. Similarly, The Planetary Society encourages messages from Earth to accompany each spacecraft mission. LightSail will be loaded with literal snapshots of today’s cultural phenomenon…selfies. That’s right, YOU can send your #SelfieToSpace aboard LightSail when it officially launches in 2016. I’ll see you on board!